1. Field of the Invention
The present invention relates to an electronic still camera capable of recording and regenerating information from a recording medium by coding and decoding image data and sound data relative to a photographed image.
2. Description of the Related Art
Japanese Patent Application Laying Open (KOKAI) No. 2-280484 shows an electronic still camera capable of recording and regenerating a picture image and a sound. As shown in this camera, a sound is stored to a sound memory while a continuous photographing mode is set and a continuous photographing operation is performed. The stored sound is recorded to a recording medium such that this sound corresponds to a picture image continuously photographed. The continuously photographed picture image and the sound during the continuous photographing operation are simultaneously regenerated from the recording medium so that an atmosphere at a photographing time can be sufficiently reproduced in this regeneration.
In this electronic still camera, a regenerated image such as a moving picture image can be obtained by continuously performing the photographing operation at a high speed. For example, an NTSC signal is obtained if a field image is recorded and regenerated every {fraction (1/60)} second. When an image is recorded to the recording medium, it is necessary to take measures for recording sound data to the recording medium in synchronization with image data.
For example, the recording medium used for the electronic still camera is constructed by a memory card. A memory region of this memory card is divided into plural memory units each having a predetermined memory capacity such that images having plural kinds of image sizes are efficiently stored to the memory card.
For example, Japanese Patent Application Laying Open (KOKAI) No. 3-187690 shows an apparatus for recording and regenerating an image so as to increase recording and regenerating speeds of data recorded and regenerated from the memory card used for the electronic still camera. In this apparatus, a central processing unit (CPU) designates a top address in a first memory unit when all plural memory units having image data to be written or read from the memory card are continued. Thereafter, an address is designated by sequentially incrementing the top address by an address register arranged within the memory card. A switching operation of the memory units normally performed is omitted by stopping operations of an address generator and a data counter by the central processing unit (CPU). Thus, when all the plural memory units having image data to be written or read from the memory card are continued, the image data can be written or read from the memory card at a high speed.
In the above image recording-regenerating apparatus, when the image data as a file are recorded to the memory card and are regenerated from the memory card, it is necessary to read and write the image data by the central processing unit (CPU) using software. Accordingly, a processing time of the image recording-regenerating apparatus is increased so that no moving image can be recorded and regenerated in real time.
In the electronic still camera, when an image is recorded to the memory card as a recording medium, it is necessary to take measures for recording sound data and image data to the recording medium at a high speed.
Japanese Patent Application Laying Open (KOKAI) No. 3-265287 shows an electronic still camera device. In this electronic still camera device, a semiconductor memory has a region for recording information indicative of an empty unit recording region to be first recorded when image data are recorded. Thus, the empty unit recording region is retrieved for a short time.
However, when data are recorded in this electronic still camera device, a central processing unit (CPU) must write header information by using software. Therefore, a processing time of the central processing unit (CPU) is increased and no moving image can be recorded to the recording medium in real time.
The electronic still camera is mainly used at present as a device for inputting image and sound data to an information equipment. For example, Japanese Patent Application Laying Open (KOKAI) No. 4-212582 proposes a technique for directly inputting image data of an electronic camera to a personal computer and performing an editing operation of the image data, etc. without using any adapter, etc.
However, no adaptability (or affinity) between the present electronic still camera and the information equipment is good. Accordingly, it is necessary to use hardware and software for an interface (I/F).
The following problems are concretely caused.
(1) Image formats used for the information equipment are different from each other in accordance with application programs. When no format of an image file recorded by the electronic still camera is suitable for an application, it is necessary to make a program for converting the file format.
(2) The electronic still camera of a standard type is designed such that an image is regenerated and seen on the screen of a television such as NTSC, etc. Accordingly, no aspect ratio of a pixel is equal to xe2x80x9c1xe2x80x9d. Therefore, when such a recorded file is regenerated by the information equipment such as a personal computer as it is, an image of the recorded file is defaced and is not clearly displayed.
(3) When image data are directly transferred to the information equipment through a recording medium interface (I/F), no image data can be normally displayed on a side of the information equipment when no synchronous position of the image data is transferred to the information equipment.
It is therefore a first object of the present invention to provide an electronic still camera in which a moving image and a sound can be recorded and regenerated in real time without increasing a memory capacity.
A second object of the present invention is to provide an electronic still camera capable of recording and regenerating image data and sound data with respect to a recording medium in real time.
A third object of the present invention is to provide an electronic still camera optimized to input multimedia information such as an image and a sound to an information equipment and having excellent cost performance.
In accordance with a first construction of the present invention, the above first object can be achieved by an electronic still camera comprising photographing means for photographing a photographed object and outputting image data; image data coding means for coding the image data; means for recording the coded image data to a recording medium; means for converting a sound to an electric signal; sound data coding means for coding sound data converted to the electric signal; means for recording the coded sound data to the recording medium; means for temporarily recording the coded image data from the image data coding means to a first-in first-out memory as a FIFO memory; means for DMA-transferring data within the FIFO memory to the recording medium where DAM is direct memory access; means for DMA-transferring the coded image data from the recording medium to the FIFO memory; and means for reading data from the FIFO memory to image data decoding means.
In accordance with a second construction of the present invention, the data within the FIFO memory are DMA-transferred for a period except for a vertical blanking period.
In accordance with a third construction of the present invention, a capacity of the FIFO memory is set to a capacity integer times that of the image data coded for one field period or one frame period.
In accordance with a fourth construction of the present invention, an interruption signal relative to completion of the DMA-transfer by a predetermined number of data is outputted from the DMA-transfer means to control means for controlling operations of the respective means.
In accordance with a fifth construction of the present invention, the above first object can be also achieved by an electronic still camera comprising photographing means for photographing a photographed object and outputting image data; image data coding means for coding the image data; means for recording the coded image data to a recording medium; means for converting a sound to an electric signal; sound data coding means for coding sound data converted to the electric signal; means for recording the coded sound data to the recording medium; means for temporarily recording the coded sound data from the sound data coding means to a first-in first-out memory as a FIFO memory; means for DMA-transferring data within the FIFO memory to the recording medium where DAM is direct memory access; means for DMA-transferring the coded sound data from the recording medium to the FIFO memory; and means for reading data from the FIFO memory to image data decoding means.
In accordance with a sixth construction of the present invention, the data within the FIFO memory are DMA-transferred for a vertical blanking period.
In accordance with a seventh construction of the present invention, a capacity of the FIFO memory is set to a capacity corresponding to the sound data coded for one field period or one frame period.
In accordance with an eighth construction of the present invention, an interruption signal relative to completion of the DMA-transfer by a predetermined number of data is outputted from the DMA-transfer means to control means for controlling operations of the respective means.
In accordance with a ninth construction of the present invention, the above first object can be also achieved by an electronic still camera comprising photographing means for photographing a photographed object and outputting image data; image data coding means for coding the image data; means for recording the coded image data to a recording medium; means for converting a sound to an electric signal; sound data coding means for coding sound data converted to the electric signal; and means for recording the coded sound data to the recording medium; the electronic still camera being constructed such that an address bus and a data bus of memory means used as a work area are respectively common to an address bus and a data bus of an interface with the recording medium.
In accordance with a tenth construction of the present invention, control signals can be simultaneously outputted by setting one bus to a bus for reading and the other bus to a bus for writing in control of the common address and data buses.
In accordance with an eleventh construction of the present invention, the above first object can be also achieved by an electronic still camera comprising photographing means for photographing a photographed object and outputting image data; image data coding means for coding the image data; means for recording the coded image data to a recording medium; means for converting a sound to an electric signal; sound data coding means for coding sound data converted to the electric signal; and means for recording the coded sound data to the recording medium; the electronic still camera being constructed such that means for detecting an insertion/extraction detecting signal of the recording medium, a busy signal of the recording medium, or a signal indicative of a reduction in voltage of a battery of the recording medium outputs an interruption signal relative to each of these signals to control means for controlling operations of the respective means.
In accordance with a twelfth construction of the present invention, the above first object can be also achieved by an electronic still camera comprising photographing means for photographing a photographed object and outputting image data; image data coding means for coding the image data; means for recording the coded image data to a recording medium; means for converting a sound to an electric signal; sound data coding means for coding sound data converted to the electric signal; means for recording the coded sound data to the recording medium; and means for extending a pulse width of a memory control signal for DMA-transfer by an outputting period of a weight signal when this weight signal is outputted from the recording medium in a DMA-transfer state of data transmitted to the recording medium where DMA is direct memory access; the extending means outputting the weight signal to control means for controlling operations of the respective means in a state in which no data are DMA-transferred.
In accordance with a thirteenth construction of the present invention, the above first object can be also achieved by an electronic still camera comprising photographing means for photographing a photographed object and outputting image data; image data coding means for coding the image data; means for recording the coded image data to a recording medium; means for converting a sound to an electric signal; sound data coding means for coding sound data converted to the electric signal; means for recording the coded sound data to the recording medium; and common reading and writing registers for getting access to a first-in first-out memory as a FIFO memory or a work memory seen from control means for controlling operations of the respective means; these registers being arranged at continuous addresses.
In accordance with a fourteenth construction of the present invention, the above first object can be also achieved by an electronic still camera comprising photographing means for photographing a photographed object and outputting image data; image data coding means for coding the image data; means for recording the coded image data to a recording medium; means for converting a sound to an electric signal; sound data coding means for coding sound data converted to the electric signal; means for recording the coded sound data to the recording medium; transfer means for transferring 16 bit data to the recording medium by exchanging high and low order bytes of these 16 bit data with each other; and control means for selecting whether this transfer means is used or not.
In accordance with a fifteenth construction of the present invention, the above first object can be also achieved by an electronic still camera comprising photographing means for photographing a photographed object and outputting image data; image data coding means for coding the image data; means for recording the coded image data to a recording medium; means for converting a sound to an electric signal; sound data coding means for coding sound data converted to the electric signal; means for recording the coded sound data to the recording medium; a register for storing address data outputted to the recording medium; and control means for selecting whether registered contents of this register are incremented by the number of transferred data or not.
In accordance with a sixteenth construction of the present invention, the above first object can be also achieved by an electronic still camera comprising photographing means for photographing a photographed object and outputting image data; image data coding means for coding the image data; means for recording the coded image data to a recording medium; means for converting a sound to an electric signal; sound data coding means for coding sound data converted to the electric signal; means for recording the coded sound data to the recording medium; a register for controlling operations of plural power sources providing outputs to the recording medium; and control means for setting registered contents of this register on the basis of a kind and a control mode of the recording medium.
As mentioned above, in accordance with each of the first and fifth constructions of the electronic still camera in the present invention, image data and sound data are recorded and regenerated with respect to a memory card as a recording medium by a first-in first-out (FIFO) memory and a DMA(direct memory access)-transfer means. Accordingly, a data transfer time is reduced and a moving image and a sound are recorded and regenerated in real time in comparison with a case in which the image data and the sound data are recorded and regenerated with respect to the memory card by using software.
In accordance with each of the second and sixth constructions of the electronic still camera in the present invention, data within the FIFO memory are DMA-transferred for a period except for a vertical blanking period. Further, sound data are DMA-transferred for the vertical blanking period. Accordingly, a file can be easily controlled every field.
In accordance with the third construction of the present invention, a capacity of the FIFO memory for an image is set to a capacity integer times that of the image data coded for one field period or one frame period. Accordingly, data can be easily processed when these data are set to a file every one field or one frame. Therefore, a continuous image can be recorded even when a memory card having a low writing speed is used. Further, no capacity of the FIFO memory is excessively increased.
In accordance with each of the fourth and eighth constructions of the present invention, completion of the DMA-transfer by a predetermined number of data relative to an image or a sound is transmitted to control means for controlling each of operations of the constructional means of the camera by using an interruption signal. Accordingly, another control operation of the camera can be performed during the DMA-transfer.
In accordance with the seventh construction of the present invention, a capacity of the FIFO memory for a sound is set to a capacity corresponding to the sound data coded for one field period or one frame period. Accordingly, the capacity of the FIFO memory is set to a suitable value.
In accordance with the ninth construction of the present invention, an address bus and a data bus of a memory such as a SRAM used as a work area are respectively common to an address bus and a data bus of a memory card interface (I/F). Accordingly, the number of pins of a control integrated circuit (IC) can be reduced.
In accordance with the tenth construction of the present invention, control signals can be simultaneously outputted by setting one bus to a bus for reading and the other bus to a bus for writing in control of the common address and data buses. Accordingly, data can be transferred at one access time. Therefore, data can be transferred at a high speed between a work memory and the memory card as a recording medium.
In accordance with the eleventh construction of the present invention, when an insertion/extraction detecting signal of the memory card, a busy signal of the memory card, or a signal indicative of a reduction in voltage of a battery of the memory card is detected, this detection is transmitted to control means by using an interruption signal. Therefore, it is not necessary for the control means to perform polling processing so that the control means can be devoted to another processing. When an obstacle is caused, measures for this obstacle can be rapidly taken so that a generating probability of defects such as data destruction, etc. within the memory card can be reduced.
In accordance with the twelfth construction of the present invention, when a wait signal is outputted from the memory card in a DMA-transfer mode, a pulse width of each of memory control signals for the DMA-transfer is extended for an outputting period of the wait signal. Accordingly, data can be normally transferred to a memory card on which a device having a low operating speed is mounted. In contrast to this, when no DMA-transfer mode is set, the weight signal is outputted to the control means. Therefore, an access operation is normally performed even when the control means directly gets access to data of the memory card.
In accordance with the thirteenth construction of the present invention, the electronic still camera has common reading and writing registers for getting access to various kinds of memories such as a first-in first-out (FIFO) memory or a work memory seen from control means. Accordingly, when the control means gets access to these memories, no operations for incrementing and decrementing addresses are performed. Therefore, a program capacity can be reduced and a high speed access operation can be simultaneously performed. Further, these registers are arranged at continuous addresses so that data can be accessed between the memories by using only address incremental commands.
In accordance with the fourteenth construction of the present invention, the electronic still camera has a means for transferring 16 bit data to the memory card by exchanging high and low order bytes of these 16 bit data with each other when these data are transferred between the memory card and a control section of the camera. Accordingly, a program capacity for this exchange can be reduced and a processing speed of the electronic still camera can be increased. Further, the high and low order bytes can be exchanged by control means so that optimum control can be performed in accordance with a data kind.
In accordance with the fifteenth construction of the present invention, the electronic still camera has a register for storing address data outputted to the memory card. It is not necessary to increment an address outputted to the memory card every time data are read and written. Accordingly, a program capacity of a ROM in the control means can be reduced and a processing speed of the electronic still camera can be increased. When it is not necessary to increment an address, a functional selection can be made by the control means so that no problem is caused.
In accordance with the sixteenth construction of the present invention, the electronic still camera has a register for controlling operations of plural power sources providing outputs to the memory card. Registered contents of this register are set from the control means by a kind and a control mode of the memory card. Accordingly, a voltage of each of the power sources optimum for the kind and the control mode of the memory card can be controlled in accordance with a device kind recorded to the memory card.
In accordance with a seventeenth construction of the present invention, the above second object can be achieved by an electronic still camera comprising photographing means for photographing a photographed object and outputting image data; image data coding means for coding the image data; means for recording the coded image data to a recording medium; means for converting a sound to an electric signal; means for coding sound data converted to the electric signal; means for recording the coded sound data to the recording medium; means for storing file header information of the image data or the sound data to a memory in advance; and direct memory transfer means; the file header information being recorded to the recording medium.
In accordance with an eighteenth construction of the present invention, the file header information includes a Huffman table used at a coding time.
In accordance with a nineteenth construction of the present invention, the electronic still camera further comprises means for making a control information file in which information relative to an image file, a sound file or a character information file is recorded to the recording medium; and a directory entry number is used in control of the control information file.
In accordance with a twentieth construction of the present invention, the above second object can be also achieved by an electronic still camera comprising photographing means for photographing a photographed object and outputting image data; image data coding means for coding the image data; means for recording the coded image data to a recording medium; means for converting a sound to an electric signal; means for coding sound data converted to the electric signal; and means for recording the coded sound data to the recording medium; an unused region of the recording medium being used as a work area for a file control work.
In accordance with a twenty-first construction of the present invention, empty cluster information corresponding to a capacity of the image and sound data to be recorded is stored to the work area for the file control work in the recording medium when a recording mode is set or a release switch is pushed.
In accordance with a twenty-second construction of the present invention, internal data of the recording medium are rearranged such that a continuous required cluster can be secured when no continuous cluster corresponding to a capacity of continuous image and sound data to be recorded can be secured.
In accordance with a twenty-third construction of the present invention, when no internal data of the recording medium can be rearranged, such contents are alarmed.
In accordance with a twenty-fourth construction of the present invention, the above second object can be also achieved by an electronic still camera comprising means for reading coded image data from a recording medium; image data decoding means for decoding the read image data; means for reading coded sound data from the recording medium; and means for decoding the read sound data; the electronic still camera being constructed such that Huffman tables are searched with respect to all files designated in regeneration when a continuous image regenerating mode is set or a release switch is pushed; and the electronic still camera gives an alarm in which no data can be regenerated in real time when no Huffman tables are equal to each other.
In accordance with a twenty-fifth construction of the present invention, the above second object can be also achieved by an electronic still camera comprising means for reading coded image data from a recording medium; image data decoding means for decoding the read image data; means for reading coded sound data from the recording medium; and means for decoding the read sound data; the electronic still camera being constructed such that Huffman tables are searched with respect to all files designated in regeneration when a continuous image regenerating mode is set or a release switch is pushed; and a Huffman table of each of images developed prior to the regeneration is made within an unused region of the recording medium when no Huffman tables are equal to each other.
In accordance with the electronic still camera having the seventeenth construction of the present invention, file header information of image and sound data is stored to a memory constructed by a RAM or a ROM in advance. The file header information is recorded to the recording medium such as a memory card by the direct memory transfer means so that a processing time of these data is reduced.
In accordance with the eighteenth construction of the present invention, the image data are set to a JPEG file by using a Huffman table so that a moving image can be recorded to the recording medium at a high speed.
In accordance with the nineteenth construction of the present invention, a directory entry number is used instead of a file name in control of an image file, a sound file and a character information file so that a retrieving operation can be performed at a high speed.
In accordance with the twentieth construction of the present invention, it is not necessary to arrange a RAM having a large capacity within the electronic still camera by using an unused region of the recording medium as a work area for a file control work.
In accordance with the twenty-first construction of the present invention, when a recording mode is set or a release switch is pushed, empty of a cluster is retrieved in the recording medium in accordance with a capacity of the image and sound data to be recorded so that these data can be immediately recorded to the recording medium.
In accordance with the twenty-second construction of the present invention, internal data of the recording medium are rearranged such that a continuous required cluster can be secured. Thus, execution efficiency of an operating system is improved.
In accordance with the twenty-third construction of the present invention, there is a case in which no data can be recorded to the recording medium when no internal data of the recording medium can be rearranged and there is no continuous cluster. In this case, this unrecordable state is alarmed to a user so that errors in recognition and use can be prevented.
In accordance with the twenty-fourth construction of the present invention, no data can be regenerated in real time when a continuous file is regenerated and Huffman tables are different from each other every regenerated file. Accordingly, when no Huffman tables are equal to each other, this unequal state is alarmed so that errors in recognition and use are prevented.
In accordance with the twenty-fifth construction of the present invention, when no Huffman tables are equal to each other at a regenerating time of a continuous file, a Huffman table of each of images developed prior to the regeneration can be made in advance within an unused region of the recording medium. Accordingly, the Huffman table can be efficiently developed and data can be rapidly regenerated from the recording medium.
In accordance with a twenty-sixth construction of the present invention, the above third object can be achieved by an electronic still camera comprising photographing means for photographing a photographed object and outputting image data; image data coding means for coding the image data; means for recording the coded image data to a recording medium; means for converting a sound to an electric signal; means for coding sound data converted to the electric signal; means for recording the coded sound data to the recording medium; and means for selecting an image or sound format recorded to the recording medium.
In accordance with a twenty-seventh construction of the present invention, the above third object can be also achieved by an electronic still camera comprising photographing means for photographing a photographed object and outputting image data; image data coding means for coding the image data; means for recording the coded image data to a recording medium; and means for changing a pixel aspect ratio of the image data recorded to the recording medium.
In accordance with a twenty-eighth construction of the present invention, the above third object can be also achieved by an electronic still camera comprising photographing means for photographing a photographed object and outputting image data; image data coding means for coding the image data; means for recording the coded image data to a recording medium; means for converting a sound to an electric signal; means for coding sound data converted to the electric signal; means for recording the coded sound data to the recording medium; means for transferring incompressible image data to a recording medium interface section; and means for generating a code showing image synchronization and inserting this code into the incompressible image data.
In accordance with a twenty-ninth construction of the present invention, the incompressible image data transfer means has means for inserting sound data compressed in a time axis direction into the incompressible image data for an image blanking period.
In accordance with a thirtieth construction of the present invention, the incompressible image data transfer means has means for generating and inserting a code showing a field number or a frame number of an image into the incompressible image data for an image blanking period.
In accordance with a thirty-first construction of the present invention, the incompressible image data transfer means has means for generating and inserting status information and control commands transmitted to a device connected to the recording medium interface into the incompressible image data for an image blanking period.
In accordance with a thirty-second construction of the present invention, a transmitted data bus width in the incompressible image data transfer means is constructed by 16 bits composed of 8 bits for a brightness signal and the remaining 8 bits for a subsampled color difference signal.
In accordance with a thirty-third construction of the present invention, a transmitted data bus width in the incompressible image data transfer means is constructed by 16 bits composed of N bits for image data and the remaining bits for sound data where N is a positive integer.
As mentioned above, in accordance with the twenty-sixth construction of the present invention, the electronic still camera has means for selecting an image or sound format recorded to a memory card as a recording medium. Accordingly, when these formats are used in various kinds of application programs in an information equipment, no file conversion is required if data are recorded by the electronic still camera in accordance with the image and sound formats.
In accordance with the twenty-seventh construction of the present invention, the electronic still camera has means for changing a pixel aspect ratio of the image data recorded to the recording medium. Accordingly, when this aspect ratio is used in various kinds of application programs in the information equipment, no aspect conversion is required if data are recorded by the electronic still camera in accordance with the pixel aspect ratio.
In accordance with the twenty-eighth construction of the present invention, the electronic still camera has means for transferring incompressible image data to a recording medium interface section, and means for generating a code showing image synchronization and inserting this code into the incompressible image data. Accordingly, a synchronous position of the image data is known.
In accordance with the twenty-ninth construction of the present invention, the incompressible image data transfer means has means for inserting sound data compressed in a time axis direction into the incompressible image data for an image blanking period. Accordingly, the sound data can be also transferred in real time.
In accordance with the thirtieth construction of the present invention, the incompressible image data transfer means has means for generating and inserting a code showing a field number or a frame number of an image into the incompressible image data for the image blanking period. Accordingly, when an error in data transfer is caused, these data can be normally displayed immediately after this error is recovered.
In accordance with the thirty-first construction of the present invention, the incompressible image data transfer means has means for generating and inserting status information and control commands transmitted to a device connected to a recording medium interface into the incompressible image data for the image blanking period. The status information can be monitored on an information equipment side and an operation of the information equipment can be controlled.
In accordance with the thirty-second construction of the present invention, a transmitted data bus width is constructed by 16 bits composed of 8 bits for a brightness signal and the remaining 8 bits for a subsampled color difference signal. Accordingly, image data can be efficiently transmitted.
In accordance with the thirty-third construction of the present invention, a transmitted data bus width is constructed by 16 bits composed of N bits for image data and the remaining (16xe2x88x92N) bits for sound data where N is a positive integer. Accordingly, sound and image data can be transferred in real time.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the present invention as illustrated in the accompanying drawings.